1-alkylsulphonyl-2-trifluoromethyl-benzimidazoles

ABSTRACT

1-Alkylsulphonyl-2-trifluoromethyl-benzimidazoles of the formula   WHEREIN R is alkyl of 1 to 4 carbon atoms are produced by reacting a 2-trifluoromethyl-benzimidazole of the formula   WHEREIN R1 is hydrogen or an equivalent amount of a cation with an alkylsulphonic acid halide of the formula R-SO2-HalIII wherein R is as above defined and Hal is halogen, in the presence of an organic diluent which is inert to the reaction, at a temperature of from -10*C to +50*C. The 1-alkylsulphonyl-2-trifluoromethyl-benzimidazoles are useful for their activity against ectoparasites.

United States Patent [191 Buchel et al.

I 51 Nov. 18, 1975 i l-ALKYLSULPHONYL-Z-TRI- FLUOROMETHYL-BENZIMIDAZOLES [75] Inventors: Karl-Heinz Buchel; Wilhelm v Stendel, both of Wuppertal, Germany [73] Assignee: Bayer Aktiengesellschaft, Germany [22] Filed: Aug. 24, 1973 [2]] Appl. No.: 391,142

[30] Foreign Application Priority Data Newbold et al 260/3091 Primary Examinerl-lenry R. Jiles Assistant ExaminerC. M. S. Jaisle [57] I ABSTRACT 1-Alkylsulphonyl-2-trifluoromethyl-benzimidazoles of I the formula wherein R is alkyl of l to 4 carbon atoms are produced by reacting a 2-trifiuor0methyl-benzimidazole of the formula wherein R is hydrogen or an equivalent amount of a cation with an alkylsulphonic acid halide of the formula wherein R is as above defined and Hal is halogen, in

' the presence of an organic diluent which is inert to the reaction, at a temperature of from -lO C to +50C.

The l-alkylsulphonyl-2-trifluoromethyl-benzirnidazoles are useful for their activity against ectoparasites.

7 Claims, No Drawings l-ALKYLSULPHONYL-ZTRIFLUOROMETHYL- BENZIM IDAZOLES t The present invention is concerned with l-alkyl-sulphonyl-Z-trifluoromethyl-benzimidazoles, to a process for their production, to compositions embodying said compounds as the active ingredient and totheir use as active agents against ectoparasites.

It is known in the art that 0,0-diethyl-O-(3-chloro-4- methyl-umbelliferone)thiophosphate can be used against ectoparasites, especially as a tickicide (see U.S. Pat. No. 2,748,146). However, its activity in certain fields of use is no longer entirely satisfactory, for example because in one-host ticks of the genus Boophilus signs of resistance to phosphoric acid esters have occurred. Thus, the Biarra strain and the Mackay strain of Boophilus microplus in Australia show resistance to 0,0-diethyl-O-( 3-chloro-4-methyl-umbelliferone )thiophosphate. Furthermore, it is known that l-methyl-sulphonyl-4,5,6-trichloro-2-trifluoromethyl-benzimidazole possesses an activity directed against insects which are harmful to plants, and against spider mites (compare Published Netherlands Application No. 66 10554). However, no special tickicidal activity of such compounds has been known.

The compounds of the present invention are l-alkylsulphonyl2-trifluoromethyl-benzimidazoles of the formula SO -R wherein R is alkyl of l to 4 carbon atoms. These compounds may be produced by reacting a 2-trifluorometh-' yl-benzimidazole of the formula wherein R is hydrogen or an equivalent amount of a cation, with an alkylsulphonic acid halide of the formula R SO, Hal Ill wherein R is as above defined and Hal is halogen, in the presence of an organic diluent which is inert to the reaction, at a temperature of from -lC to +50C. The reaction may, if desired, be carried out in the presence 'of an acid-binding agent.

The 1-alkylsulphonyl-2trifluoromethyl-benzimidazoles of the present invention are'useful as active (3-chloro-4*methyl-umbelliferone)thiophosphate.

v If 2-trifluoromethyl-benzimidazole and methanesulphonic acid chloride, are used as starting substances, the course of the reaction can be represented by the following formula scheme:

, s o cn I -HC1 As set forth above, R is alkyl of 1 to 4 carbon atoms,

which definition embraces both the straight as well as branched chain alkyl moieties, i.e., methyl, ethyl, npropyl, isopropyl, n-butyl, sec.butyl.and tert.butyl.

When R is a-cation, it is preferably thesodium cation.

Hal is preferably chlorine.

The alkylsulphonyl halides of theformula (III) which are used as starting materials for producing the compounds of the present invention, are known. Representative examples include: CH SO Cl, .C H SO Cl and n- C H SO Cl. 2-trifluoromethylbenzimidazole which is used as a starting material to produce the, compounds of the present invention is also known.

Diluents which can 'be used according'to the process of the present invention include organic solvents which are inert toward this reaction. Preferred diluents include hydrocarbons such as benzene and toluene; ethers such as dioxan and tetrahydrofuran; nitriles such as acetonitrile, and ketones such as methyl ethyl ketone. It is also within the scope of the-process of the present invention to use mixtures of these solvents.

With respect to the acid-binding agents, known acidbinding agents useful for processes of ,this type can be used in the present process. Preferred acid-binding agents include alkali metal hydroxides, alkali metal carbonates, alkali metal alcoholates, alkaline earth metal carbonates, tertiary organic bases and secondary organic bases. Sodium methylate, barium carbonate, pyridine and triethylamine are particularly useful.

While the temperature range for the reaction is preferably l0C to +50C, it is particularly preferred to carry, out the reaction at a temperature of from about l'0C to about +20C. The reaction is generally carried out at atmospheric pressure.

In carrying out the reaction according to the invention, 1 mol of alkylsulphonic acid chloride and l to 2 mols of acid-binding agent are generally employed per mol of 2-trifluoromethyl-benzimidazole of the formula The l-alkylsulphonyl-2-trifluoromethyl-benzimidazoles of the present invention may be recovered either by a method in which the solvent is partially discrystallization, or by a method in which the halide which is sparingly soluble in organic solvents is filtered off, the solvent is partially distilled off and the precipitate is filtered off.

The following compounds are representative of those of the present invention:

l-methylsulphonyl-2-trifluoromethyl-benzimidazole l-ethylsulphonyl-2-trifluoromethyl-benzimidazole l-n-propylsulphonyl-2-trifluoromethyl-benzimidazole l-iso-propylsulphonyl-Z-trifluoromethyl-benzimidazole l-n-butyl-sulphonyl-2-trifluoromethyl-benzimidazole;

and

l-tert.-butylsulphonyl-2-trifluoromethyl-benzimidazole.

In addition to displaying strong acaricidal properties, especially against Acarina, which attack, as animal ectoparasites, domesticated animals such as cattle and sheep, the compounds of the present invention also exhibit a very low toxicity to warm-blooded animals, thus enhancing their veterinary use.

As examples of economically important ectoparasites of this nature which play a considerable role especially in tropical and sub-tropical countries there may be mentioned: the Australian and South American onehost cattle tick, Boophilus microplus, the South African cattle tick, Boophilus decoloratus (both from the family of the Ixodidae), as well as multi-host'ticks such as species of Rhipicephalus, Amblyomma, Hyalomma and Ixodes.

Over the course of time, one-host ticks have in numerous areas become resistant against the phosphoric acid esters and carbamates hitherto used for combating them, so that in many places they have recently been combated with doubtful success. To secure economical raising of animals in places subject to attack, there is an urgent need for agents by means of which all stages of development, that is to say larvae, metalarvae, nymphs, metanymphs and adults, even of resistant strains, for example of the genus Boophilus, can be combated reliably. For example, in Australia the Mackay strain, the MT. Alfort strain and the Biarra strain of Boophilus microplus are highly resistant to the previous phosphoric acid ester agents.

The compounds of the present invention are effective both against the strains of normal sensitivity and against the resistant strains, for example of Boophilus. When administered in the usual manner to the host animal, they have a direct lethal effect on all parasitic forms so that the development cycle of the ticks is interrupted in the parasitic phase on the animal.

The production of fertile eggs and hence the development and hatching of larvae is inhibited.

According to the present invention, veterinary compositions are prepared which comprise a l-alkyl-sulphonyl-2-trifluoromethyl-benzimidazole of the present invention in combination with a pharmaceutically acceptable non-toxic inert diluent or carrier. These veterinary compositions may be in the usual formulations, such as solutions, emulsions, suspensions, soluble, suspendable or emulsifiable concentrates, spraying or other powders, pastes, granulates and creams. These may be produced in known manner, for example'by mixing the active compounds with-extenders, that is,

4 liquid or solid or liquefied gaseous diluents or carriers, optionally with the use of surface-active agents, that is, emulsifying agents and/or dispersing agents, and/or foam-forming agents. In the case of the use of water as an extender, organic solvents can, for example, also be used as auxiliary solvents.

As liquid diluents or carriers, there are preferably used aromatic hydrocarbons, such as xylenes, toluene, benzene or alkyl naphthalenes, chlorinated aromatic or aliphatic hydrocarbons, such as chlorobenzenes, chloroethylenes or methylene chloride, aliphatic hydrocarbons, such as cyclohexane or paraffins, for example mineral oil fractions, alcohols, such as butanol or glycol as well as their ethers and esters, ketones, such as acetone, methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone, or strongly polar solvents, such as dimethyl formamide, dimethyl sulphoxide or acetonitrile, as well as water.

By liquefied gaseous diluents or carriers are meant liquids which would be gaseous at normal temperatures and pressures, e.g. aerosol propellants, such as halogenated hydrocarbons, e.g. freon.

As solid diluents or carriers, there are preferably used ground natural minerals, such as kaolins, clays, talc, chalk, quartz, attapulgite, montmorillonite or diatomaceous earth, or ground synthetic minerals, such as highly-dispersed silicic acid, alumina or silicates.

Preferred examples of emulsifying and foam-forming agents include non-ionic and anionic emulsifiers, such as polyoxyethylene-fatty acid esters, polyoxyethylenefatty alcohol ethers, for example alky'larylpolyglycol ethers, alkyl sulphonates, alkyl sulphates and aryl sulphonates as well as albumin hydrolyzation products; and preferred examples of dispersing agents include lignin, sulphite waste liquors and methyl cellulose.

weight, preferably 0.005 to 3 per cent by weight.

The compounds of the present invention are administered by topical application, such as spraying, dusting, rubbing or pouring, or by using a bath or dip in a conventional manner. The concentration and the absolute amount, in the mixture, of the particular active compound applied depends on the intended application and on the type of animal treated.

The following in vitro and in vivo test results illustrate the activity of the compounds of the present invention. The numbers associated with the compounds in the test data below correspond to the example numbers.

EXAMPLE A In Vitro Tick Test on Boophilus microplus 3 parts of active compound were mixed with 7 parts of a mixture of .equal parts by weight of ethyl glycol monomethyl ether and nonylphenol polyglycol ether. The emulsion concentrate thus obtained was diluted with water to'the particular desired use concentration.

Adult fully engorged] fem ale ticks of vthe-species.B0-

} ()philus micmplus (B'iarra 'strain) were dipped-for one preparation was determined-"by determining the-inhibition of the production of fertile eggs as compared to the laying of eggs by untreated ticks. Theactivity is indi-- cated in with l00% denoting that no fertile eggs were laid any longer and 0% denoting that the ticks laid ,eggs in the normal manner, like the untreated control I 6 j ;13 =p;a ;rts of active compound werernixed with Z parts of aymixture of equal parts weight jof' et'hylglycol monomethyl ether and nonylphenyl polyglycol ether.

I, The emulsion concentrate th'usobtained. was diluted I with water to the particular desired use concentration;

Cattle which had been infected repeatedly wit h iesistant tick larvae of the species Boophilus microplus,

. Biarr'as'train (infection l 2X at intervals of 2 days) were 'sprayed with-the activecompoundpreparation thus obtained. I wThe action of the active compound preparation was I determined by determining the number of adult female ticks which developed on the treated cattle. This numher was compared with the number of adult female 15 ticks which developed on untreated cattle. A com- In Vivo Tick Test on Boophilus microplus pound was the more active, the fewer female ticks developed after the treatment. L

' Then'umber'of'adult females .which developed in treated and untreated animals in the last three days beticks.

The results are given in.Table A.

- TABLE A in Vitro Test 7 1 Inhibition Active Compounds *ActiveComof Egg propound duction concentrution- 7r (Boopliilus in ppm microplusi Biarra strain) H .,c,o |0.000- s0 P-0- 0 3,000 50 H C O 1,000 50 300 50 H3 100 0 30 0 (known) c| N 10.000 0 C| i g r Y i l l SO,CH;,

(known) 10.000 100 @I" L -CF. m0 1.000 I00 SOgCH; 300 j l00 I00 0 (1) 10.000 100 i" 3.000 100 a 1,000 I00 L 300 I00 OgC1H5 100 100. 30 0 (2) N 10,000 I 100 l CF 3.000 100 N 3 L000 100 300 50 SO CH -CH CH I00 50 30 O EXAMPLEB 7 fore the point in time at which the'treatmentwas carried out was used as a measure of the intensity of the infection before the treatment.

The following non-.limitative examples more particularly illustrate the present invention:

The active compounds and results'of the'tes't e'xperi- I A E l ments can be seen from Table B.

. a HTAB LE B I Y lAll stages of development in vivo (cattleiolv Hopphilus microplus (Biarra strain) 5 y H C,O u O o o I H C O CH (known) Active Compound Number of Ticks with Fertile Laid Eggs Concentration Days before in ppm treatment Days after treatment 2 -l +1 +2 +3 +4 +5 +6 +7 .+8 +9 +10 2,000 482 377 397 236 112 9 14 0 0 12 24 34 16 Active Compound Con- Number of Ticks with Fertile Laid Eggs centration in ppm Days after treatment 7 +11 +12 +13 +14 +15 +16 +17 +18 +1 +20 Total in days +1 to +20 K I b-CF;

Active Compound Con- Number of Ticks with Fertile Laid Eggs centration Days before in ppm treatment Days after treatment -2 1 0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +10 +11 +12 Untreated 110 148 181 262 86 114 68 152 158 131 70 25 9 18 47 control 500 312 373 625 8 4 0 1 6 2 7 17 9 7 2 2 Active Compound Con- Number of Ticks with Fertile Laid Eggs centration in ppm Days after treatment +13 +14 +15 +16 +17 +18 +19 +20 Total in days efficacy in a +1 to +20 Untreated 120 83 11 32 42 43 1661 control O,C,H,

Active Number of Ticks with Fertile Laid Eggs Compound Concentration Days before in ppm treatment Days after treatment 2 1 0 +1 +2 +3 +4 +5 +6 +8 +9 +10 Untreated 608 1125 1038 395 386 236 52 22 137 224 173 131 119 control 329 710 382 268 451 114 19 45 318 443 120 174 100 1.000 445 723 337 0 0 0 0 1 0 0 0 0 0 500 67 7O 89 0 0 0 0 0 1 0 0 0 0 Active Compound Number of Ticks with Fertile Laid Eggs Concentration in ppm Days after treatment +11 +12 +13 +14 +15 Total in days Efficacy in +1 to +15 Untreated 98 194 128 77 154 2526 control 247 296 107 ,75 168' 2945 93 g (0.5 mol) of Z-trifluoromethyl-benzimidazole were added, while stirring, to a freshly prepared sodium methylate solution (11.5 g of sodium were dissolved, for this purpose, in approximately 200 ml of anhydrous methanol). The solution was mixed with approximately 500 ml of anhydrous benzene and a mixture of benzene and methanol were distilled off, while stirring, until the boiling point of pure benzene (80C) was reached, if necessary with repeated addition of benzene. The susl5 pension, which thus remained, of sodium salt in approximately 200 ml of benzene, was mixed with 300 ml of anhydrous acetonitrile; a solution resulted. The solution was cooled to 0C and a solution of 57.3 g (0.5 mol) of methanesulphonic acid chloride in approximately 100 ml of anhydrous acetonitrile was added dropwise while stirring. Thereafter the resulting suspension was stirred for 3 hours at room temperature and then warmed under reflux for 1 hour.

The resulting sodium chloride was filtered off and the solvent of the filtrate was partly distilled off. The resulting precipitate was filtered off and recrystallized from ether. 81 g (6l% of theory) of l-methylsulphonyl-Z-trifluoromethyl-benzimidazole of melting point 1 16 l 18C were obtained.

EXAMPLES 2 6 The compounds set forth in the table below were prepared by reacting 2-trifluoromethyl-benzimidazole I with the sulphonic acid chloride specified below:

What we claim is l. A compound of the formula wherein R is alkyl of l to 4 carbon atoms.

2. The compound according to claim 1 which is SO CH 3. The compound according to claim l which is 4. The compound according to claim 1 which is 0 S0 CTI -CH -CH 5. The compound according to claim 1 which is l SO ,-CH( CH 2 6. The compound according to claim which is 7. The compound according to claim 1 which is 

1. A COMPOUND OF THE FORMULA
 2. The compound according to claim 1 which is
 3. The compound according to claim 1 which is
 4. The compound according to claim 1 which is
 5. The compound according to claim 1 which is
 6. The compound according to claim 1 which is
 7. The compound according to claim 1 which is 